Make file locking more robust for network shares like AFP

1 files changed, 22 insertions, 8 deletions

diff --git a/AuLock.c b/AuLock.c
index 0012356..69b1fd6 100644
--- a/AuLock.c
+++ b/AuLock.c
@@ -90,14 +90,28 @@ long	dead)
 		(void) close (creat_fd);
 	}
 	if (creat_fd != -1) {
-	    if (link (creat_name, link_name) != -1)
-		return LOCK_SUCCESS;
-	    if (errno == ENOENT) {
-		creat_fd = -1;	/* force re-creat next time around */
-		continue;
-	    }
-	    if (errno != EEXIST)
-		return LOCK_ERROR;
+#ifndef X_NOT_POSIX
+	    /* The file system may not support hard links, and pathconf should tell us that. */
+	    if (1 == pathconf(creat_name, _PC_LINK_MAX)) {
+		if (-1 == rename(creat_name, link_name)) {
+		    /* Is this good enough?  Perhaps we should retry.  TEST */
+		    return LOCK_ERROR;
+		} else {
+		    return LOCK_SUCCESS;
+		}
+	    } else {
+#endif
+	    	if (link (creat_name, link_name) != -1)
+		    return LOCK_SUCCESS;
+		if (errno == ENOENT) {
+		    creat_fd = -1;	/* force re-creat next time around */
+		    continue;
+	    	}
+	    	if (errno != EEXIST)
+		    return LOCK_ERROR;
+#ifndef X_NOT_POSIX
+	   }
+#endif
 	}
 	(void) sleep ((unsigned) timeout);
 	--retries;